The present invention is related to a relatively simple fluid drive transmission which is self contained and does away with the necessity of providing a clutch between the originating source of power such as the engine and the drive and driven members. It further eliminates the necessity of using a gear shift mechanism and gear trains except when changeover into reverse operation is desired. The fluid circulation is a continuous one and the fluid moves through a closed path while transmitting power from the drive to the driven member. A variety of fluid coupled power transmission units are known to the prior art with a number of different arrangements of vanes on the drive and driven members of the unit. One example of such a fluid transmission unit is disclosed in U.S. Pat. No. 2,389,174 issued on Nov. 20, 1945 to P. V. Withworth for "Power Transmitting Unit". The drive and driven units generally used in the prior art include cup shaped members placed in opposition on either the drive or driven member. A different type of fluid coupling device is shown in U.S. Pat. No. 3,955,365 issued on Apr. 28, 1975, to Masachika Arao for "Fluid Coupled Drive Apparatus". In that patent there is shown a different and well known arrangement whereby the fluid coupling is through a pair of opposed disc like members which have arranged about their inner surface a number of vanes.
A still further type of fluid-mechanical power transmission is shown in U.S. Pat. No. 3,209,874 issued on Oct. 5, 1965, to G. Foster et. al. for "Fluid-Mechanical Power Transmission System". That patent uses a drive and driven member having flat surfaces opposed one to the other with the driven member carrying a number of radial vanes.
A still further type of fluid transmission system is shown and described in U.S. Pat. No. 2,357,654 issued on Sept. 5, 1944 to J. R. Horton for "Turbo Power Transmission Apparatus". That patent shows a system in which a number of variable pitch vanes are included that are shifted mechanically to vary the pitch of the blades.